Question: A study showed that 60 percent of The Wall Street

A study showed that 60 percent of The Wall Street Journal subscribers watch CNBC every day. Of these, 70 percent watch it outside the home. Only 20 percent of those who don't watch CNBC every day watch it outside the home. Let D be the event "watches CNBC daily" and O be the event "watches CNBC outside the home."
(a) Sketch a tree based on these data.
(b) Calculate the probability of all joint probabilities (e.g., D ∩ O).
(c) Verify that the joint probabilities sum to 1.